May 22, 2014

Mars Rover Curiosity May Have Taken Microbial Stowaways

History is filled with accounts of man introducing alien species into a new ecosystem, so a new report coming from Nature News should come as no surprise – the Curiosity rover may have introduced microbes into its surrounding environment on Mars.

The Nature report mentioned a study presented at this year’s annual meeting of the American Society of Microbiology in Boston that discovered that the 377 strains of bacteria found on the Mars probe can resist the extreme temperatures and damage caused by harmful radiation found throughout the Solar System.

The study team said their results really are a first step toward determining how certain germs might endure decontamination and space travel.

Using swabs of Curiosity performed before it was launched, the study team was able to identify 65 species of bacterial stowaways, most of which were linked to the genus Bacillus.

Researchers exposed these microbes to desiccation, ultra-violet radiation, temperature extremes, and pH extremes. Almost 11 percent of the 377 strains survived more than one of these serious threats. Thirty-one percent of the resistant bacteria did not form their tough, protective spore coats. The study team suspected that they used other biochemical means of protection, such as metabolic shifts.

“When we embarked on these studies there wasn’t anything known about the organisms in this collection,” said study leader Stephanie Smith, a microbiologist at the University of Idaho.

While NASA spacecraft typically go through a sterilization regimen before launch, reports have surfaced indicating that Curiosity project developers did not follow these guidelines to the letter. However, the study team said they aren’t sure if the microbes could survive on Mars. In addition to contaminating Martian soil, microbes could also taint rock samples gathered on future missions, providing false signs of life.

“We don’t know yet if there’s really a threat,” Smith said. “Until we know, it’s important to take a precautionary approach.”

The researchers said their work may inform NASA cleaning procedures and point to a need for greater planetary protection on future missions. The study will also be used to inform a NASA mission planned for 2020 that will eventually bring back rover samples from Mars for analysis.

“This can keep us from identifying dead bugs from a sample return mission as something that originated on Mars,” said John Rummel, a researcher at East Carolina University who was not involved in the study. “We could be sure that they’re not Martians.”

NASA officials met last week to iron out the details for the sample-returning mission. According to reports, the plan is to build a rover similar to Curiosity, complete with instruments for collecting, testing and storing samples. A follow-up mission would collect the stored samples and bring them back to Earth.

“The next 20 years of Mars exploration hinges on where this rover goes,” Philip Christensen, a planetary scientist at Arizona State University, told Nature's Jyoti Madhusoodanan. “It has to tell us something fundamental about the broader history of Mars.”

“The most important thing for this spacecraft is not so much to learn about the rocks on Mars, but to learn enough to know if those rocks have the stuff in them that you want to bring back to Earth,” said Matthew Golombek, a planetary geologist at the Jet Propulsion Laboratory in Pasadena, California.